Lots of versions of the optiplex--from big to tiny. Also the less than 300w power supply is too small. You have to measure the space available and look at the power requirements of any card you want to add. The Optiplex is a business model and not suitable for upgrading to a gaming computer.

The 7750 Low Profile is fine for the Tower as it uses 1 Slot. Do not be fooled there is another card that is a 7750 but its not LOW Profile and Will not fit. The one that works in all models except the USFF says Fits MINI ITX on the box.

The 7750 speedstep posted should physically fit. Power should be fine as well.

I have been running the very similar radeon sapphire 4650 ddr2 512 low profile in an optiplex 745 desktop for a couple years without probelms. I think the size (about 7 inches long) and cooler width and power draw are substantially the same.

Edit: I just measured my optiplex 745 and looked at the motherboard. Assuming you have the same stock motherboard, you probably want to look for a low profile card that is a single slot cool and no longer than 7 inches on the printed circuit board portion. Otherwise, you might hit the components along the side of the expansion slot (there appears to be a couple of tall capacitors on the board), or will hit the cpu shround on the length.

By the way, that microcenter page indicates that the sapphire 7750 low profile is 5.1 inches wrong, I don't think that's right, I think it is more like 7 inches long. It should still fit, but 5.1 is pretty short for a 7750, I think.

Hi there just bought an asus 6570 from ebay,although now looking at the inside measurments i'am very concerned that it will not fit,the width including the heat sink is 1 inch,it looks as though the only space is half that, the length and height will be fine,i'll let you know when it turns up in the post.745 sff.